Is it true "W" can be used as a vowel?

In elementary school I remember the teacher telling me that the vowels were AEIOU and sometimes Y and W. But I can't think of a single word where W is used as a vowel. Are there any?

— Michael S., Baltimore

Cecil replies:

Sure. Try "how," which is phonetically equivalent to "hou," as in house. Ou and ow are diphthongs — that is, two vowel sounds that kind of slide together when you say them. W and Y are often called semivowels because they go both ways, as it were, depending on the company they keep within the word. (Low morals are obviously a problem at every level of our society.) In cow, for instance, W is a vowel, but make the word coward and you can hear W working as a consonant. Similarly with Y become I in copy and copier. I could also expound on the vowel-likes, yet another class of letters with an identity crisis, but I think we've had enough angst for one column already.

Letter writer claims telepathic abilities

Dear Cecil:

Regarding your column on the use of W as a vowel, the word Mr. S. wanted to hear was cwm. There are of course others. Check out your OED. And hey, in general you're OK.

— Luis P., Chicago

Cecil replies:

Don't think that token nicety is going to save you, you skunk. Cwm, pronounced "koom" and signifying "mountain hollow," is a borrowing from Welsh, in which tongue W is a vowel equivalent to oo (or perhaps we should say, double-U). Use of W this way in English is anomalous and is not what linguists have in mind when they talk about W being a part-time vowel.

How a mutation like cwm got into a nice language like English in the first place is a question that bears some looking into. Except for persons who spend a lot of time prowling around mountain hollows, it's useful chiefly to composers of crossword puzzles and other disreputable amusements, e.g., the "pangram." A pangram is a sentence containing every letter of the alphabet at least once and ideally no more than once. You can see how cwm would come in handy in this regard. For example, we have:

Cwm, fjord-bank glyphs vext quiz

… which means, "Carved figures in a mountain hollow and on the bank of a fjord irritated an eccentric person." ("Vext," of course, is an alternate form of "vexed," and "quiz" means "an eccentric person.") Similarly we have: